Schlegel Mark K, Essen Lars-Oliver, Meggers Eric
Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein Strasse, D-35043 Marburg, Germany.
J Am Chem Soc. 2008 Jul 2;130(26):8158-9. doi: 10.1021/ja802788g. Epub 2008 Jun 5.
The crystal structure of an 8-mer (S)-GNA duplex is presented. As a tool for phasing, the anomalous diffraction of two copper(II) ions within two artificial metallo-base pairs was employed. The duplex structure confirms a canonical Watson-Crick base pairing scheme of GNA with antiparallel strands. The duplex secondary structure is distinct from canonical A- and B-form nucleic acids and can be described as a right-handed helical ribbon wrapped around the helix axis, resulting in a large hollow core. Most intriguingly, neighboring base pairs slide strongly against each other, resulting in extensive interstrand base-base hydrophobic interactions along with unusual hydrophobic intrastrand interactions of nucleobases with their backbone. These results reveal how a minimal nucleic acid backbone can support highly stable Watson-Crick-like duplex formation.
本文展示了一种8聚体（S）-GNA双链体的晶体结构。作为相位测定的工具，利用了两个人造金属碱基对中两个铜（II）离子的反常衍射。双链体结构证实了GNA与反平行链的典型沃森-克里克碱基配对模式。双链体二级结构不同于典型的A-和B-型核酸，可描述为围绕螺旋轴缠绕的右手螺旋带，形成一个大的中空核心。最有趣的是，相邻碱基对彼此强烈滑动，导致广泛的链间碱基-碱基疏水相互作用以及核碱基与其主链之间不寻常的疏水链内相互作用。这些结果揭示了最小的核酸主链如何支持高度稳定的类沃森-克里克双链体形成。
